Francis
Required for Porsche approval
Porsche recommend a 0w-40 lubricant all year round (-30C to 40C+) for all engines produced since 1973 (subject of course to engine condition). Their prime Approval Group 3 synthetic criteria has already been covered here (ACEA A3/B3) and includes their own specific minimum viscosity at 100C - the HTHS minimum is covered by ACEA's "A3". Porsche's Approval also covers a specific anti foaming test protocol which many oils will not meet and may be the cause for rod bearing failures. Tests for volatility and oxidation resistance are also included.
From History of engine oil
The next problem to rear its ugly head was that of oil aeration. Given enough oil in the system, big enough coolers and a nice big oil tank to let air bubbles separate from the oil, a mineral oil can cope with a lot, for a short time at least. Look at a Formula 1 car from 25 years ago and see the size of the oil pipes, oil coolers, pumps and filters. Where have they gone now? The main problem lies in the dry sump system of a race engine. To enable the crankshaft to be completely free from oil drag and to allow the engine to be mounted as low as possible, the engine oil is pumped from a shallow tray - instead of a deep sump, underneath the engine and sent to a remote tank. The feed side of the oil supply is then pumped from the tank rather than from the sump. In order to make sure the sump is always empty, the scavenge - sump emptying - pump has to be of much greater capacity than the feed pump. Air is thus sucked through this part of the system with the oil. Unfortunately, mineral oil will absorb air, sometimes as much as 25% in such conditions, which if left in the oil would present a bearing oil film full of holes like a Dutch cheese. A large oil tank with an air separator system is therefore essential. Similarly, a mineral oil when overheated breaks down to form tars and varnishes, therefore large oil pumps, large diameter oil pipes and hefty oil cooling radiators are a must, as is the maximum amount of oil possible on board. All this extra weight and aerodynamic drag was a complete anathema to racing car designers, but was it possible to get rid of it?
PAO based synthetics are less affected by fuel or by-products of fuel than oils with mineral bases, they give high film strength from low viscosity oils and have an inherent viscosity index which means far fewer viscosity modifiers are required. The PAO synthetic base also lasts far longer without breaking down. The perfect base oil? Maybe. Learn about other stronger synthetic base oils, how to get rid of bulky oil cooler systems from your Formula 1 car, and where Red Line® synthetic oils come into all of this, in the next exciting episode.
